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Research progress in additive manufacturing of melt growth ceramics by laser directed energy deposition |
Fangyong NIU, Xuexin YU, Ziyuan ZHAO, Dake ZHAO, Yunfei HUANG, Guangyi MA, Dongjiang WU( ) |
School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China |
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Abstract Melt growth ceramics (MGC) is a new type of ceramic material with microstructure obtained by melting and solidification of raw materials. The clean and high-strength bonding interface shared by atoms makes it have excellent high-temperature mechanical properties and microstructure stability close to the melting point. It shows great application potential in the field of high thrust weight ratio aero-engine and heavy gas turbine hot end components in the future. Laser directed energy deposition (LDED) technology can effectively overcome the limitations of traditional preparation methods of MGC in terms of cycle, energy consumption and structural complexity. It provides a new solution for direct additive manufacturing of MGC components, and has become a research hotspot at home and abroad. Based on the introduction of the process principle of LDED technology, the microstructure characteristics and properties of different MGCs prepared by this technology at home and abroad were summarized in this paper, and the main research on the control of microstructure and cracking behaviour was comprehensively discussed. Based on the existing research progress, the development trend and key scientific problems to be further solved in this field were discussed. It was pointed out that inhibiting cracking and improving microstructure and properties are the primary problems faced at present. The development of materials and new processes is the key to breaking through the existing bottleneck and promote the development and application of MGC-LDED.
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Received: 31 August 2021
Published: 18 July 2022
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Corresponding Authors:
Dongjiang WU
E-mail: djwudut@dlut.edu.cn
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Process principle of LDED
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Material | Microstructure characteristics | Microhardness | Fracture toughness/(MPa·m1/2) | Flexural strength/MPa | Relative density/% | Al2O3 [35] | Directionally grown α-Al2O3 coarse | 15.5-17 GPa | 2.1 | | 94 | Al2O3 [36] | columnar grains and intergranular | | | 85 | | Al2O3 [37] | two-dimensional structure | 1700-2300HV0.2 | 2.7 | | | Al2O3[34] | | 18.91 GPa | 3.55 | 210 | 99.5 | ZrO2[29] | t-ZrO2 interlayer banded structure and t-ZrO2 embedded in c-ZrO2 matrix in convex mirror shape | 19.8 GPa | | | 98.7 | Al2O3-ZrO2[38] | Primary phase Al2O3 or ZrO2 and | 19 GPa | 3.7 | | | Al2O3-ZrO2 [32] | intergranular eutectic matrix | 21.4 GPa | 4.61 | | | Al2O3-ZrO2 [39] | | 1680-1880HV | 3.8 | 208 | | Al2O3-ZrO2 [40] | | 1972HV | 5.91 | 237 | 98 | Al2O3-TiO2 [41] | Primary α-Al2O3 phase and continuously distributed Al6Ti2O13 matrix | 1670HV | 3.97 | 200 | | Al2O3-ZrO2 eutectics [42] | Banded structure and eutectic colony | 16.7 GPa | 4.5 | | | Al2O3-YAG eutectics [30] | composed of fine eutectic structure | | | | 100 | Al2O3-YAG eutectics [43] | | 17.35 GPa | 3.14 | | | Al2O3/ZrO2/YAG eutectics[44] | | (18.9±0.95) GPa | 3.84±0.44 | | 98 | Al2O3/GdAlO3/ZrO2 eutectics[45] | | | | | | Spinel[46] | MgAl2O4 phase and intergranular Ca and Si rich phase | 1400HV | 2.5 | | | Piezoelectric ceramics[47] | Fine and uniform structure composed of perovskite phase and pyrochlore phase | (358±28)HV | | | 90 | Calcium phosphate bioceramics[28] | α-tricalcium phosphate (α-TCP) matrix and nucleated tetracalcium phosphate (TTCP) grains | | | | |
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Microstructure and properties of different MGC materials prepared by LDED
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34-37]; (b)columnar crystal structure[35]; (c)two dimensional structure of columnar crystal surface[34] ">
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Al2O3 ceramic samples and typical microstructure characteristics (a)samples[34-37]; (b)columnar crystal structure[35]; (c)two dimensional structure of columnar crystal surface[34]
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38-39]; (b)hypoeutectic structure[48]; (c)eutectic structure[42] ">
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Al2O3-ZrO2 composite ceramics (a)typical samples[38-39]; (b)hypoeutectic structure[48]; (c)eutectic structure[42]
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45] (a)typical samples; (b)macroscopic morphology of banded structure; (c)microscopic characteristics of banded structure; (d)eutectic colony structure; (e)irregular eutectic structure ">
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Al2O3/GdAlO3/ZrO2 ternary eutectic ceramics[45] (a)typical samples; (b)macroscopic morphology of banded structure; (c)microscopic characteristics of banded structure; (d)eutectic colony structure; (e)irregular eutectic structure
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27]; (b)microstructure[27]; (c)light transmission characteristics[55] ">
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Alumina magnesia spinel ceramics (a)typical samples[27]; (b)microstructure[27]; (c)light transmission characteristics[55]
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28] (a)typical samples; (b)microstructure; (c)biological characteristics ">
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Calcium phosphate ceramics[28] (a)typical samples; (b)microstructure; (c)biological characteristics
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Method | Material | Effect | Increase heat input [32] | Al2O3-ZrO2 | Columnar dendrites become shorter, banded structure thickness increased | Increase scanning speed[31, 45] | Al2O3/GdAlO3/ZrO2 eutectics | Banded structure thickness decreased, eutectic spacing decreased | Increase laser power[27] | Spinel | Porosity decreased enhanced, grain coarsened, light transmittance enhanced | Substrate water cooling[43] | Al2O3-YAG | Eutectic spacing decreased, hardness increased, fracture toughness increased | Ultrasound assisted [26] | Al2O3-ZrO2 | Grain refinement, hardness improved, wear resistance improved | Ultrasound assisted [60] | Al2O3-ZrO2 eutectics | Eutectic spacing decreased, fracture toughness increased | Ultrasound assisted [61] | Al2O3-YAG | Grain refinement, hardness improved, wear resistance improved | C fiber doping[62] | Al2O3-ZrO2 eutectics | Eutectic spacing decreased, fracture toughness increased | SiCp doping[63] | Al2O3-ZrO2 | Porosity decreased, eutectic size decreased | Heat treatment[35] | Al2O3 | Density increased, microhardness increased, fracture toughness increased | Heat treatment[29] | YSZ | From dark brown to dark yellow | Heat treatment[31] | Al2O3/GdAlO3/ZrO2 eutectics | Eutectic structure coarsened, banded structure disappeared, microstructure uniformity improved |
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Structure and performance control methods in MGC-LDED
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60]; (b)water cooling assisted fabricating Al2O3-YAG eutectic ceramics[43] ">
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Outfield assisted LDED (a)ultrasound assisted fabricating Al2O3-ZrO2 eutectic ceramics[60]; (b)water cooling assisted fabricating Al2O3-YAG eutectic ceramics[43]
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Control method | Material | Control effect | Increase laser power [26] | Al2O3-ZrO2 | The crack length and opening width are reduced | Change scanning direction [64] | Al2O3 | When the scanning angle is 45° and 67°, the sample has no obvious cracks | Increase laser power[29] | YSZ | The number of cracks decreased first and then increased | Increase scanning speed and Z-increment[67] | Al2O3 | Higher scanning speed and larger interlayer lift are easier to obtain crack free samples | Substrate heating[42] | Al2O3-ZrO2 | 20 mm×8 mm×8 mm crack free samples | Substrate heating[30-31] | Al2O3-YAG | Al2O3-YAG samples without cracks were prepared | Substrate heating[49] | Al2O3-ZrO2 | The grain is refined and the cracks are obviously reduced | ZrO2doping[68] | Al2O3-ZrO2 | The eutectic ratio has the best crack suppression effect | SiCP doping[63] | Al2O3-ZrO2 | Cracks decreased significantly | ZrO2doping [39] | Al2O3-ZrO2 | When the ZrO2 content is 10%, the crack is suppressed | Ultrasound assisted [26] | Al2O3-ZrO2 | Conducive to crack suppression, crack-free 7 mm×7 mm×10 layers sample was fabricated |
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Cracking suppressing methods of MGC
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63, 67, 69] (a)SiCP doping; (b)ZrO2 doping; (b)TiO2 doping ">
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Crack suppression effect of composite materials[63, 67, 69] (a)SiCP doping; (b)ZrO2 doping; (b)TiO2 doping
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